Heating, ventilation, and air conditioning (HVAC) systems provide environmental comfort in an indoor space, such as a room or a building. HVAC systems are typically closed-loop control systems. For example, in a room heated by a hot water radiator, an HVAC system may compare sensed parameters from a room thermostat with radiator settings, such as a valve setting, and may adjust the radiator settings based on the comparison in order to control air temperature in the room.